Plant and Animal Reproduction

• Reproduction is essential for the continuation of life for both plants and animals.
• Plants and animals differ significantly in their reproductive mechanisms and strategies.

Modes of Reproduction in Plants

• Plants reproduce both sexually and asexually.
• Sexual reproduction involves the fusion of male and female gametes through pollination and fertilization.
• Asexual reproduction occurs through fragmentation, budding, or specialized structures like bulbs or runners.

Modes of Reproduction in Animals

• Animals primarily reproduce sexually through the fusion of male and female gametes, forming a zygote.
• Some simpler animals can reproduce asexually through fragmentation or budding.

Plant Development

• Plant growth is indeterminate, continuing throughout their lifespan from meristematic tissues at shoot and root tips.
• Growth occurs through cell division, enlargement, and differentiation.
• Morphogenesis involves developing roots, stems, leaves, and flowers, influenced by genetic factors and environmental cues.

Animal Development

• Animal growth is generally determinate, ceasing once a certain size or developmental stage is reached.
• Growth primarily involves cell division, enlargement, and differentiation.
• Animal morphogenesis is dynamic, involving tissue folding, cell migration, and apoptosis to form intricate body structures and organs.

Plant Nutrition

• Plants are autotrophic, producing their own organic compounds through photosynthesis.
• They use sunlight, water, and carbon dioxide to synthesize glucose and other carbohydrates.
• Plants absorb minerals and water from the soil through their roots.

Animal Nutrition

• Animals are heterotrophic, relying on organic matter produced by other organisms for nutrition.
• They obtain nutrients by consuming other organisms or organic matter derived from them.
• Animals digest complex organic molecules into simpler forms through ingestion, digestion, absorption, and assimilation.

Plant Nutrient Storage

• Plants store excess carbohydrates as starch in chloroplasts and specialized storage organs like roots, tubers, and seeds.
• Stored carbohydrates provide energy reserves during low photosynthetic activity or for developing new tissues.

Animal Nutrient Storage

• Animals store excess energy primarily as glycogen in the liver and muscles.
• Glycogen is readily broken down into glucose to meet energy demands when food intake is limited.

Plant Gas Exchange

• Gas exchange mainly occurs through stomata, small pores on the underside of leaves.
• Stomata regulate gas exchange with the atmosphere, taking in CO2 and releasing O2 during photosynthesis.
• Plants take in oxygen and release carbon dioxide during respiration.

Animal Gas Exchange

• Gas exchange generally occurs through specialized respiratory organs like lungs, gills, or tracheal systems.
• Terrestrial vertebrates exchange gases in the lungs, where oxygen diffuses into the bloodstream and carbon dioxide diffuses out.
• Aquatic animals extract oxygen from water and release carbon dioxide through gills.

Plant Circulation

• Plants lack a centralized circulatory system; they utilize vascular tissues (xylem and phloem).
• Xylem transports water and minerals from the roots, while phloem transports sugars from photosynthesis.

Animal Circulation

• Animals have a centralized circulatory system with a heart, blood vessels, and blood.
• Vertebrates have a closed system where blood circulates through arteries, veins, and capillaries.
• The heart pumps oxygen-rich blood to tissues via arteries, and oxygen-depleted blood returns via veins.

Plant Pumping Mechanism (Circulation)

• Movement of water and nutrients is driven by transpiration (water loss from leaves) and root pressure.
• Transpiration creates negative pressure, pulling water and nutrients up through the xylem.
• Root pressure from osmotic processes in the roots helps push water and minerals up the plant.

Animal Pumping Mechanism (Circulation)

• Animals have a heart, which actively pumps blood throughout the body.
• The heart contracts rhythmically to push blood through blood vessels for efficient distribution of oxygen, nutrients, and hormones.

Organs Involved in Fluid Regulation in Plants

• Fluid regulation occurs primarily in roots and leaves.
• Roots uptake water and minerals from the soil, while leaves regulate transpiration and gas exchange.

Organs Involved in Fluid Regulation in Animals

• Fluid regulation involves kidneys that filter blood to remove waste and regulate water and electrolyte balance.
• Skin, lungs, and the digestive system also regulate fluids through perspiration, respiration, and excretion.

Fluid Regulation in Plants

• Plants adjust water uptake and transpiration rates to maintain internal balance in response to environmental changes.
• They may close stomata to reduce water loss during drought or increase water uptake in response to low soil moisture.

Fluid Regulation in Animals

• Animals respond to environmental changes through sweating to cool down or concentrating urine to conserve water.
• Hormonal regulation coordinates responses to environmental cues.

Nervous Control in Plants

• Plants lack a centralized nervous system, but use specialized cells and conductive tissues for electrical signalling.
• Electrical signals, termed action potentials, regulate responses to environmental cues and coordinate growth.

Nervous Control in Animals

• Animals have a nervous system comprising neurons that transmit electrical impulses.
• The nervous system includes the central nervous system (brain and spinal cord) and the peripheral nervous system.

Chemical Control in Animals

• The endocrine system includes glands (pituitary, thyroid, adrenal, and gonads) that produce hormones.
• Hormones regulate functions like blood glucose levels (insulin), metabolism (thyroid hormones), stress response (cortisol), and reproduction (estrogen and testosterone).
• Hormones maintain metabolic homeostasis, regulating energy balance, blood pressure, and electrolyte levels.
• Insulin and glucagon regulate glucose metabolism, aldosterone controls sodium and potassium balance, and parathyroid hormone regulates calcium levels.

Plant Defense Mechanisms

• Plant immune responses involve physical barriers, chemical defenses, and systemic signalling pathways.
• Physical barriers include the cell wall and cuticle.
• Chemical defenses include phytoalexins, pathogenesis-related (PR) proteins, and secondary metabolites.
• Plant immune responses are mediated by pattern recognition receptors (PRRs) that detect pathogen-associated molecular patterns (PAMPs)

Animal Defense Mechanisms

• Animal immune systems combat pathogens through a complex network of cells, tissues, and soluble factors.
• The immune system includes innate immunity (immediate, nonspecific defense) and adaptive immunity (specific, long-lasting immunity).
• Key components include leukocytes (white blood cells), antibodies, complement proteins, and lymphoid organs.

Plant Sensory Mechanisms

• Plants lack specialized sensory organs, relying on distributed sensory structures and mechanisms.
• Plant cells possess receptors that detect light, gravity, touch, and chemicals.
• Photoreceptors detect light wavelengths for phototropism and photoperiodism, while mechanoreceptors respond to mechanical stimuli.

Animal Sensory Mechanisms

• Animals possess specialized sensory organs such as eyes, ears, nose, tongue, and skin, which detect stimuli.
• Photoreceptor cells in the eyes detect light, auditory receptors in the ears detect sound waves, olfactory receptors in the nose detect chemical odors, taste receptors on the tongue detect flavors, and mechanoreceptors in the skin detect touch, pressure, and temperature.

Plant Motor Mechanisms

• Plant movements are driven by growth processes and differential cell expansion.
• Tropisms (phototropism and gravitropism) involve differential growth rates in response to directional stimuli.
• Nastic movements are rapid, reversible movements in response to stimuli like light, touch, or temperature.

Animal Motor Mechanisms

• Animal movements are mediated by muscular contractions controlled by the nervous system.
• Motor neurons transmit signals from the central nervous system to muscles, triggering coordinated movements.

Importance of Biology

• Understanding life, human health, environmental conservation, agricultural innovation, evolutionary insights.